Usually, reactive mesogen layers require an alignment layer or rubbed plastic substrate to align in the planar state. In this regard, two main methods are currently used in the display industry to align liquid crystals for optical film applications:
(i) Rubbing process, wherein a plastic substrate or alignment layer is rubbed in one direction providing alignment direction for coated liquid crystals. The alignment quality varies depending on the rubbing process and the properties of the substrate or film. The rubbing process is difficult to optimise and can produce variable results. Furthermore, the rubbing process is considered an unfavourable process by LCD producers because it can produce particles that are difficult to control in high-class clean rooms.
(ii) Photoalignment process, as described in U.S. Pat. No. 7,364,671 B2, wherein a photo-orientable monomer, oligomer or polymer is photo-oriented while maintaining conditions that the polymerization or cross-linking of the polymerizable liquid-crystalline material is essentially inhibited. The photoalignment and polymerization step are carried out in two different steps and under different conditions. Accordingly, such photoaligning layers can be difficult to prepare due to the requirements that the production conditions have to be adjusted concerning the individual composition of various liquid-crystalline materials. In addition, an annealing step is usually required to allow liquid crystals to align fully. Consequently, photoaligning layers following this process are expensive.
Therefore, there is still the need for alternative production methods, which do not have the drawbacks of prior art methods or have them to a lesser extent.
One aim of the present invention is to provide a one-step method of production for a polymer film, which    a) is in particular suitable for mass production, and    b) is applicable for a broad range of polymerizable liquid-crystalline materials,    c) does not require an alignment layer like e.g. rubbed polyimide layer,    d) allows patterning,    e) allows overcoating a chosen layer without the need for an extra alignment layer,    f) allows the production of thick films with a non-uniform alignment, and    g) allows the production of concave or convex flat type polymer lenses.
Other aims of the present invention are immediately evident to the person skilled in the art from the following detailed description.